A Mersenne prime is a prime number one less than the equivalent power of two. An online project, Great Internet Mersenne Prime Search (GIMPS), uses computers to try to find new Mersenne primes. Users found the bug in Intel’s new processors when calculating the complex numbers with the GIMPS Prime95 program while on Skylake hardware.
Ars Technica reports that the community at hardwareluxx.de initially came across the potentially serious issue during routine use of the program. It was reported to the GIMPS team who conducted further testing and verified its existence, finding a Skylake-based system will crash while multiplying extremely large numbers when the exponent becomes greater than 14,942,209. The Prime95 software continued to run as normal past this exponent when running on older processors.
Intel has since confirmed the problem, saying it will issue a fix for affected processors via a motherboard BIOS firmware update. This won’t always be easy for end users to apply though and there is always an element of risk when updating a BIOS. Intel hasn’t said which chips are affected but the Skylake range is used in tablets, laptops, desktops and workstations.
Intel said in a statement: “Intel has identified an issue that potentially affects the 6th Gen Intel Core family of products. This issue only occurs under certain complex workload conditions, like those that may be encountered when running applications like Prime95. In those cases, the processor may hang or cause unpredictable system behaviour.”
The company has notified other manufacturers of other critical hardware components, such as motherboards and memory, to let them know it will require a BIOS distribution once it has successfully fixed the issue. The affected processors will not be subject to any form of recall as the bug is purely a software problem.
It’s unlikely that a typical PC user would ever encounter the bug but it’s a major issue to people who work in big data and who use their computer for pure computing, as in the case of Prime95 users. Skylake processors have substantially increased performance over their Haswell predecessors but this isn’t of much use if the processor grinds to a halt after a few hours of number crunching.
This isn’t the first time that Intel’s Skylake family of sixth-generation Core processors has been hit with an issue. Late last year, owners of Skylake-equipped gaming PCs began to report that the weight of some third-party popular CPU coolers can damage and bend the new processors, an issue that Intel is currently monitoring. Skylake has a much thinner layer of substrate material than previous generations, potentially making it less resistant to heavy pressure from above.
